Fiber bonding resin/and bonded product



Patented Nov. 10, 1953 FIBER BONDING RESIN/AND BONDED PRODUCT Baak W. Lew, Arden, Del., assignor to Atlas Powder Company, Wilmington, Del., a, corporation of Delaware N Drawing. Application January 30, 1951, Serial No. 208,657

12 Claims. 1

This invention relates to bonded mats of fibrous material, to resin castings and moldings reinforced with such mats, and more particularly to novel resin compositions adapted to the bonding of such mats.

It is an object of the invention to provide resin bonded mats of fibrous materials, particularly of glass fibers, suitable for use as plastics reinforcements.

Another object is to provide novel resin compositions of wide utility, which are particularly suited for use as bonding resins in the preparation of glass fiber mats.

A still further object is to provide novel powdered, autoploymerizable resin compositions containing polymerizing catalysts.

The above and other objects will become more apparent in the course of the following description and the appended claims.

In accordance with the present invention a novel heterogeneous resin composition is provided which comprises a intimate physical mixture of solid resin particles in powder-to-granular form, said mixture containing discrete particles of one polyester resin which is a fumarate of ethylene glycol; and discrete particles of a second polyester resin which is a fumaric acid ester of a polyol comprising from 90 to 100 mol per cent of a dihydric alcohol corresponding'to the formula:

wherein R is an alkylene radical containing from 2 to 3 carbon atoms, A is a 2-alkylidene radical containing from 3 to 4 carbon atoms, m and n are each at least one, and the average sum of m+n is not over 3, and from 0 to mol per cent of an aliphatic polyhydric alcohol containing from 3 to 6 carbon atoms and at least 3 hydroxyl groups. The second named component of the resin composition is ..characterized by the presence of a bisphenol nucleus, c

and forconvenience will be designated hereinafter as bisphenol type polyesters. Both of .the named component resins are polymerizable under the effect of heat and in'the presence of the ordinary vinyl "polymerization catalysts, and the resperoxide, lauroyl peroxide, stannic chloride pentahydrate, cobalt nitrate, and the like. The compositions may contain up to 5 per cent by weight (based on active ingredient) of said catalyst depending upon the rate of cure desired and the activity of the catalyst.

Ethylene glycol fumarate resins are well known in the plastics and resin art. They are normally prepared by heating together, in an inert atmosphere, fumaric acid with a stoichiometric excess of ethylene glycol, first under partial reflux conditions to allow water of condensation to distil out while glycol is refluxed into the charge, and finally at higher temperature and reduced pressure whereby the excess glycol is removed and a linear resinous polymer is formed. The polymer so formed is balsam-like at room temperature and cannot be powdered aslong as it remains in amorphous condition. When crystallization of the mass occurs, or is induced, the polyester becomes hard and brittle, and can readily be reduced to a powder. The ethylene glycol fumarate component of the mixtures of the present invention is in the crystalline form and reduced to such size that it will all pass a No. 10 U. S.

Standard Sieve and preferably will all pass a No.

20 U. S. Standard Sieve, while at least 75% will be held on a No. 140 U. S. Standard Sieve.

Polyester resins suitable as the second named ingredient of the heterogeneous resin compositions of the present invention are readily prepared according to methods taught in copending application Serial No. 92,746; filed Mayll, 1949, and Application Serial" No. 190,240, filed October 14, 1950, both assigned to the assignee of the present invention. They are fumaric acid polyesters of diols or diol-polyol mixtures as 'de-' scribed above. Exemplifying diols suitable'for preparing the said polyesters are 2.2-di-(4 beta hydroxyethoxyphenyl) propane, 2.2 di (4 hydroxy propoxyphenyl) propane, 2.2 di (4 beta in compositions of the invention may "contain small but significant amounts of such catalyst thoroughly incorporated with the resin particles. Among suitable catalysts may be named benzoyl hydroxy ethoxy phenyl) -butane, and the polyoxy ethylene ether of isopropylidene diphenol wherein both phenolic hydroxyls are oxyethylated and the average number of oxyethylene groups per mol is 2.6. Polyols which may be usedto replace an equivalent quantity up to 10 mol per cent of diols in preparing said polyesters include glycerol, pentaerythritol, sorbitol, mannitol, sorbitanferythritol, and the like. In its preferred embodiment, the resin composition of the present invention. 7 contains as the second named componentafu maric acid ester of a mixed diol-polyol compris ing 96 mol per cent of 2.2-di-(4 beta hydroxyethoxyphenyD-propane and 4 mol per cent 01' g V glycerol. Such a resin may be prepared in accordance with the following example.

A reaction kettle fitted with an agitator means for maintenance of an inert atmosphere, means for applying vacuum'and means for "condensing and measuring evolved water was charged with 275 lbs. of 2.2-di(4-beta hydroxy ethoxy phenyl) propane, 104 lbs. 6 oz. of Iumaric'acid and 32 grams of hydroquinone. The charge was heated and agitated in an atmosphere of carbon dioxide at a temperature of 180 to 185 C. unti1* 50% of the theoretical water was-stewed, after'which the temperature was raised to 205 to 210 C. and the reaction continued until 75% of the theoretical water had been collected. 3 lbs. '-6 oz. of glycerol was then added and heating continued at the same temperature until'the acid number of a withdrawn sample was down to 30. Ai/"ac'uum"of "Q'mm. wasthe'n'ap'plied and the reactio continued at 205 to 215 0. until the resin had a'melting' point by the AS-TM ball and ri e method cr me 0. v 7

R' sins'of the type so describedfand exemplified are hard, brittle, apparently amorphous 'solidsat room temperature, and show'no visible tendencyto crystallize onf'ag'ing. As employed in the present invention, "they are-reduced by an "suitable fgrin'di'ng means to a particle size 'such'thatall willpa'ssa No. 10'U. S.Standard sieve, 'andpr'ef erably to a particle size such that jallw ill pass ajNo." 20 U. SXStaridar'd sieve, while apiece-"% will beheld by e140 mesh screen.

The heteroge'neous resin i compositions particularlyfadapted for use as bonding resins in formflbrous reinforcing mats of glass fibers "and the l'ike'are prepared" by" intimately mixing crystalline ethylene glycol furnar'ate'resin, ground 'a-sindicated hereinbeforegand one or more of the "above described 'powdered-tmgranular bispher'iol 'typepolyester resins. The" preferred resin comp'ositio'nskontain substantially equal proportions of the two named types of resinalthough usermf compositions include *tliose wherein the proportion of glycol iumarate to "bisphenol type resin lies semantic inclusive limits of "75 to '25 and 2 5to 75. The mixing maybe efiected by 'aiiyjfsliitable' meanssucn as in a tumbling barrel, afl ibboflmixr, awrfier Pflideir mixer; 61' the like. V

Aniarked acute-meme tr theresin compos tions of the present ihventionrsids in the tact that inthe solid'state theres'i'nsare virtually inert towar'c'l's the commonvinyl"polymerizationcatalys'ts. When the resins are mixedfcatalysts 'may be incorporated in proper amounts for the intendeduse of the IniXtureQand' theprecatalyzed mixture stored-withoutspecial preeautidns' such as refrigeration, until used. Such precatalyzed compositions 'arewithinthescope of the present invention, and may containjany "amount up to 5""fl rfi3 ent' b jweig'nt ofcatalystalthough itis usually preferred to employ from Ito-2:5 per cent weighttl'ier'eof I g V H p Th -following"examplesillustrate the preparatio of typical bondiing resincompositions "acstrainers the invention.

. *EXAIVIPLE -11 'is'eearateiy "ghee "crystalline "ethylene glycol fir arate farid'the resinof' Exaniple I-until all passesa NOQQDU." SQPStEndaidEieVe." Charge a fSS gallond'rfimfwith 1001158. "er each resin, siesta the iesi'ri'ifi altefnatiiicremehtsof about 4 50 lbs. each. Close the drum and rotate it end over end at about 50 r. p. m. for 8 hours. The product is uniform throughout and consists of an intimate mixture of discrete particles of the two resins.

III

Employing the same ground resins as in Example II and powdered benzoyl peroxide as a catalyst, charge the drum as follows: Add 49 lbs. glycol fumarate, 1 lb. catalyst, 49 lbs. Example I resin, 1 lb. catalyst, 49 lbs. glycol fumarate,

"llb. catalyst, 49lbs. Example I resin, 1 lb. catalyst. Tumble forS hours as in Example II. The

product is uniform throughout and comprises intimately mixed discrete particles of the two named resins, with 2% of polymerizing catalyst thoroughly distributed therein.

EXAMPLE IV Charge the tumbling barrel I of Example II with the increments tabulated below and tumble for Shours:

Increments 1 and- 5, 24 lbs. ethylene "glycol fumarate (ground) pentahydrate (powdered) I Iicrm ehts 3 and 7, 74 lbs. Example 1 resin I (ground) H I EXAMPLE V charge the tumbling barrel of ExampleII with the increments tabulated below and tumble for 8 hours:

Increments 1 and 5, l4 lbsethylene glycol fumarate (ground) Increments '2, 4,- 6 a'nd '8, 1 'lb. lauroyl "peroxide lbowdered) Increments 3 and 7, 24 lbs. "Example I resin (ground) -sepmtey grind crystalline "ethylene :a cm fumarate polyester and the fumar'ate polyester resin of" 2.'2'-'di"(4 hydioxy "propoxy phenyl)fpi'oparie untilall. passes'a No. 20 "U. S. Standard sieve. fTiimble "equal proportions thereof with 2% ofbenzoyl peroxide "asf'catalyst according to the techfiidue'bf ExampleIII. 'Res'imcompositio'ns "oftlie type"describe'd"arid exemplified above may be employed for'awide variety of purposes. For example the mixture maybe incorporated with"granular cork, coinpressedinto slabs and cured to form gasket ma-s teiial. aners'mfm'ixturesnia be compression molded jwithbrwitn ut fillisto yi1u"a' variety of usefulshapes. The compositiohs' majy "be dusted into freshly printed'matter and fused to yield" excellent decorative effects 'siinulat'ing'em- BOSSd work. The resin compositions" have been found particularlyfwell "suited for use fin'bohdingjiibro'us materials into mats and their utility for this "perpetrate-11 be exemplified herein insome detail. Precatalyzed resin compositionsma'y be incorporated with "natural organic fibers such as cotton, cellulose pulp, wool; orwith synthetic organic fibers such as rayon, nylon or spun filameatseryifiyrpciym rs for wirmfiorgamfiters 's'uch'f as glass fiber; ro'elrwoor fibers, asbestos and tfielik rmed'mtomatsand"cared.

Glass befifiats' fso prepared are 'especiall'yuse-r fill 'a's"reiiif"' ciiigeleinents" for east: resin'fo'rms, laminates aridmoldings. 'The 'bofidedmats inay be f iried flatf out to-"shapefand laid ina "mold infs'mgle'. ofmultilayer, 7 g Iiated-with' resin aiidburedforj'alterriatiylyffibrous inats may be formed directly in the shape, of the desired artipressed and cured. These techniques are more .specifically taught in the following example.

7 EXAMPLE VII A bonded mat of glass fibers in sheet form weighing approximately 2 ounces per square foot -was prepared as follows:

One half ounce of glass fibers in the form of strands averaging 2% inches long, each strand being composed of approximately 204 filaments averaging 0.00038 inch in diameter, was weighed out and divided into 4 roughly equal portions. One portion was spread as a layer of unoriented fibers on a fiat square metal plate 6" on a side. 0.35 gram of the precatalyzed resin mixture of Example III was sprinkled uniformly over the surface of the fibers. Two more portions of the fibers were then spread over the first layer and 0.70 gram of the same precatalyzed resin sprinkled thereon. Finally the fourth portion of fibers was layered on the others and another 0.35 gram portion of the precatalyzed resin mixture sprinkled over the top. The plate containing the built up layers was tapped gently to cause sifting of the resin into the fiber interstices, covered with 'a second metal plate and weighted with two iron bars to put the mat under a uniform pressure of 0.2 lbs. per square inch. The assembly was put in a curing oven at 200 C. for minutes and removed. The mat, removed from between the plates was well bonded by the cured resin and was suitable for use as a reinforcing element in plastics molding.

Mats have been prepared in similar fashion in which the powdered-to-granular bonding resin is a mixture of ethylene glycol fumarate with approximately its own weight of the fumarate of 2.2 di- (-hydroxy propoxy phenyl) propane. The technique described may be readily adapted to commercial production of bonded glass fiber mats by sifting proportioned quantities of chopped fiber glass strands and the resin mixture of the present invention onto a moving conveyor belt, passing the mat through a curing oven and under a compression roller therein.

Glass fiber mats bonded with the heterogeneous resin compositions described herein have properties sharply differentiating them from mats bonded with either of the component resins alone, or from a homogeneous mixture of the two.

Resins of the bisphenol type produce mats of good compressibility and satisfactory properties for many purposes. Mats so prepared, however, are sensitive to the styrene present in most laminating resins, even when thoroughly cured, and in some laminations and moldings. the matted. fibers are not held in position by the bondingv resin when laminating resin solution is introduced, resulting in uneven fiber distribution in the finished reinforced plastic.

With granular ethylene glycol fumaratealone as the bonding resin it is very difficult to obtain glass fiber mats satisfactory for any purpose requiring manipulations thereof. The cured resin is brittle and shows very little heat distortion. Probably because of these properties the bonded mats exhibit poor compressibility and flexibility, resulting. in flufiy mats of poor dry strength.

6 Ihe cured resin is virtually inert to styrene and cannot contribute to adhesion between the reinforcing fibers and the laminating resins.

It has been attempted to combine the desirable properties of the two types of resins in a single resin by coreacting mixtures of a bisphenol ether- ,alcohol and ethylene glycol with fumaric acid, and by melting the two types of resin together below any temperature at which transesterification would occur, but without success. Useful resins for many purposes, especially as base resins in molding powders, have been prepared by coreacting ethylene glycol and alcohols of the type represented by the formula as is more fully described in copending application Serial No. 190,239 filed October 14, 1950 and assigned to the same assignee as the present application, but such resins are not the equivalent of the heterogeneous compositions containing discrete particles of the two types of resins for purposes of bonding glass fiber mats suitable as reinforcing means for'plastics.

Without entering into any speculation as to why it should be true, it seems that there is a unique and unexpected advantage in simultaneously curing into glass fiber mats separate and discrete particles of the two types of resin hereinbefore described, and it is on the discovery of this advantage that the following claims are based.

What is claimed is:

1. A heterogeneous resin composition consisting essentially of from 25 to parts by weight of discrete particles of crystalline ethylene glycol fumarate polyester resin; and from 75 to 25 parts by weight of discrete particles of a fumaric acid resinous polyester of a polyol consisting of from to 100.mol per cent of a diol conforming to the formula wherein R is an alkylene radical containing from 2 to 3 carbon atoms, A is a 2-alkylidene radical containing from 3 to 4 carbon atoms, m and n are each at least one, and the average sum of m and n is not over 3, and from 0 to 10 mol per cent of an aliphatic polyhydric alcohol containing from 3 to 6 carbon atoms and at least 3 hydroxyl groups; to a total of parts.

2. A heterogeneous precatalyzed resin composition for bonding loosely felted mats of glass wherein R is an alkylene radical containing from v 2 to 3 carbon atoms, A is a 2-alkylidene radical containing from 3 to 4 carbon atoms, m and n areeach at least one, and the averagesum ofm and n is not over 3, and from 0 to 10 mol per cent of an aliphatic polyhydric alcohol contain-v Ling from #3 to 6 carbon atoms anel :at least =3 hydroxyl groups.

4. A composition for bonding loosely felted mats of glass fibers comprising the heterogeneous :resin composition of claim 1, 'wherein the said J discrete particles :are 01? a size such that substantially all pa'sses through- =a No. Standard sieve, and at 'least 751% by 'weight -is held"-by a-No.= 140 01 8. standardsieve.

-5.'- A composition for bonding loosely felted mats of 'glass fibers consisting-essentially of equal -parts1by wei'ght of discrete particles of crystalline ethyleneglycol fumarate polyester resin and discrete particles of a resinous polyester of fiiinfaric acid and a mixed polyol consisting of from 94 to 98 mol per cent of 2.2=di= (4 beta hydroxyethoxy phenyl) propanea nd from 2t'o"6 mol per cent of "glycerol. I

6. 'A composition for bonding loosely felted mats of glass fibers, consisting "essentially of "at 'least"95'%- by weight of amixtureof resins-as in claim '5 and-a smallbut significant amount, not "to-exceed 5%, of a vinylipolymerization catalyst.

"7. A bondedmat of loosely felted glass'fibers comprising glass fibers arrangedinhelterskelter pattern, bound at a-plurality of the points of contact-between said fibers with a heterogeneous resin composition as described in claim 2.

" 8. 'A'bonded" mat as described in claim Tv'vhere- "in the weight ratio of said glass "fibers "to said "heterogeneous resin composition lies between the *inclusive' limits of 97 to 3 and '85- to 15.

9. A bonded. mat of loosely felted glassfibers comprising glass fibers arranged inhelter-skelter pattern, bound at aplurality'of the points of contact between said" fibers 1 with the-cured product of the-composition of claimifi; whereinthe weight ratio 1 of said glass fibers to said cured pro'duct lies betweenthe inclusivelimits of 97 too3= and- --to 15.

lilflI'he prooess of preparing a bon'ded glass fiber -mat which-comprises arranging a loose blanket consistingof:--glass fibers and discrete particles 1 of a heterogeneous :resin composition as described in claim -2, and subjecting the blanket to the curing temperature of the precatalyzed resin "'ior -a sufficient 1 time to efiect its cure.

11. The process of claimdO-wherin'the' weight ratio of said-glass fibers to said resin composition lies between the inclusive limits of 7 9'7 3 and -"85-to-15.

12. The process or preparing-a 1 bonded glass fiber *mat --which "comprises arranging a loose blanket consisting of from-*97%-to 85% of glass fibers and from-3% to J 15 of discrete particles of a'" heterogeneous'resin composition as described inclaim 6, and snbje'cting the blanket to -the curing 1 temperature of the preoatalyze'd resin "for a sufficient time to effect its'cure.

Rferences Cited the file of this patent UNITED-STATES F PA'I'ENTS Number Name Date "758,246 Goldman fApr. 26, '1904 "2,437,046 Rothrook ever Mar. 2;1948 '2','5'68',144= Cremer "Sept... 18, "71951 $604,427 Armstrong j'July 22, 1952 

5. A COMPOSITION FOR BONDING LOOSELY FELTED MATS OF GLASS FIBERS CONSISTING ESSENTIALLY OF EQUAL LPARTS BY WEIGHT OF DISCRETE PARTICLES OF CRYSTALLINE LETHYLEN GLYCOL FUMARATE POLYESTER RESIN AND DISCRETE PARTICLES OF A RESINOUS POLYESTER OF FUMARIC ACID AND A MIXED POLYOL CONSISTING OF FROM 94 TO 98 MOL PER CENT OF 2.2-DI(4 BETA HYDROXYETHOXY PHENYL) PROPANE AND FROM 2 TO 6 MOL PER CENT OF GYLCEROL. 